The startup, which has raised $16.3 million from investors like Khosla Ventures, Battery Ventures, and Sequoia Capital, is not at all like Yelp or Foursquare. Instead of recommending places to go, Sosh is more about suggesting things to do, which is a more nebulous concept.

For example, Sosh users in Seattle or San Francisco might get a recommendation to go on a hike and be given a specific trail map to follow.

Sosh also curates lists of events and concerts. People are given recommendations based on small preferences: parts of the city they like to spend time in, types of things they like to do, how much money they're willing to spend, what day of the week they like to go out.

"When we started a handful of years ago, the basic concept was to use technology to help people break their rut and try amazing things out in the real world," Sosh co-founder Rishi Mandal told Business Insider.

Mandal, an astrophysicist who has worked at both NASA and Google, realized people were having success when Sosh would recommend something like a show or a concert. They'd open their phone, tap a couple times, and suddenly they had tickets.

But, Mandal said, he also saw something his team could improve on:

"Sosh would say 'Hey, the perfect thing for you would be this ridiculously good chicken dish in the West Village, and it's awesome, but don't actually go because it's probably full and you'll wait for two hours and you'll have to make a reservation 30 days in advance.'

"In a world where people are used to pushing a button on their phones and having something instantly happen, making reservations weeks in advance just isn't a possibility."

Sosh initially partnered with Open Table to provide reservations in San Francisco and saw it explode.

"We took a step back and looked at dining specifically and realized dining has evolved from being the accessory to entertainment to becoming the entertainment itself," Mandal said. "So consumer expectations and demand have soared. But the way you access that experience hasn't changed one bit in the past ten years."

Sosh Concierge gives diners same-day access to the hardest-to-book places – which they'd otherwise have to plan ahead 30 to 60 days in advance to visit. It reduces all the planning, booking, and paying into a couple taps on your phone's screen.

Every day, new options appear on Sosh for that evening, including tasting menus at restaurants and cocktail flights at bars. Users tap to book and pre-pay, and then show up at the restaurant or bar that night. The check (and tip) are already taken care of.

Right before your meal, Sosh sends you a reminder with tips and more information about the meal — why the chef's background is so impressive, the history of a dish you're about to try, or even where to grab a drink after dinner. And if you're not totally satisfied after your meal, Sosh will refund it for you, no questions asked.

Every experience on Sosh costs the same as what it costs in the restaurant. There are no markups or hidden fees. Users essentially use Sosh Concierge to buy "tickets" to these restaurants' tasting menus.

"We didn't want to sell reservations — we had seen companies focused on that," Mandal said. "Restaurants are often very personal reflections of a chef or restaurateur so they are not [simply money-making businesses]. We understand that a restaurant isn't simply trying to blindly maximize its profits, but is instead a hospitality business. Companies that sell reservations so fundamentally misunderstand this."

The Sosh Concierge launched Tuesday in San Francisco, though Mandal is quick to point out the service will come to New York soon, too. Sosh's main app works in San Francisco, New York, DC, Chicago, and Seattle.